1. Field of the Invention
Embodiments of the invention relate to a disturbance compensation determination apparatus, a related method, a computer-readable medium storing a computer program for executing the method, and a disk drive comprising the apparatus. In particular, embodiments of the invention relate to a disturbance compensation determination apparatus comprising a disturbance evaluation unit selectively changing a current disturbance compensation (DC) mode, a related disturbance compensation determination method, a computer-readable medium storing a computer program for executing the method, and a disk drive comprising the apparatus.
2. Description of the Related Art
Embodiments of the invention relate to Korean Patent Application No. 2001-017826 and Japanese Patent Application No. 1993-242509. Korean Patent Application No. 2001-017826 suggests a technique of measuring an amount of disk imbalance by analyzing a vibration frequency of a hard disk drive (HDD). Japanese Patent Application No. 1993-242509 suggests a technique of improving a disturbance countermeasure characteristic in an optical disk drive (ODD).
In general, a HDD is a data storage device in which data may be written to and read from a disk using a magnetic head. The trend in HDD technology is toward increasing storage capacity and data storage density of HDDs and decreasing the sizes of HDDs, which increases the bits per inch (BPI) and tracks per inch (TPI) in HDDs. BPI is the data storage density in a disk rotation direction (i.e., along a track of a disk), and TPI is the data storage density along a radius of a disk. In addition, the changes mentioned above require increasingly fine control of the head of a HDD.
The purpose of track-following control in a HDD is to precisely position a head over the center of a target track. However, track-following control errors may be caused by various kinds of disturbance. In particular, a micro drive, which is a portable drive, is susceptible to vibration or shock, which may cause disturbance.
If disturbance is applied to a disk drive, the disturbance is directly reflected in a position error signal (PES), and the applied disturbance may result in a decrease in read/write performance. In general, a disk drive has a controller for detecting a characteristic of an applied disturbance and compensating for the disturbance to keep the read/write performance of the disk drive stable even when disturbance is applied to the disk drive.
Because a conventional controller that compensates for disturbance focuses on disturbance compensation, a system including a conventional controller that compensates for disturbance is less stable than a controller that does not compensate for disturbance.